Electrochemical cell, use of the electrochemical cell, and method for electrolytically contacting and electrochemically influencing a surface

ABSTRACT

An electrochemical cell for electrolytically contacting and electrochemically inspecting surfaces which makes electrolytic contact with the surface through a body utilizing capillary action. The capillary force between surface and body utilizing capillary action prevents the electrolyte from escaping from the cell without the use of a sealing ring. The body utilizing capillary action allows the electrolyte to flow from an open porous container and wet the surface when the electrochemical cell contacts the surface. Escape of material from the open cell is prevented by the capillary action of the container and of the tip when the electrochemical cell is lifted from the surface. The electrochemical cell is independent of the force of gravity and enables measurements to be made on surfaces of any orientation. The electrochemical cell may be used to perform a multiplicity of electrochemical investigations and processes. The electrochemical cell may be moved over the surface continuously, thereby allowing electrochemical investigations or processes to be performed with lateral resolution. Due to the use of a maintenance-free reference electrode, the electrochemical cell may prefabricated commercially in complete form and stored for extended periods of time after closing.

TECHNICAL FIELD

[0001] The invention relates to an electrochemical cell forelectrolytically contacting and electrochemically inspecting surfacesaccording to the preamble of the first claim.

[0002] The invention further relates to an application of theelectrochemical cell according to the preamble of the independent methodclaim.

[0003] The invention further relates to a method for electrolyticallycontacting and electrochemically modifying a surface according to thepreamble of the independent method claim.

PRIOR ART

[0004] Essentially, there are two types of electrochemical cells whichare used for electrochemically inspecting surfaces. With one cell, thesurface to be examined is immersed in an electrolyte. The advantage hereis that even rough or uneven surfaces may be electrochemically examined.The disadvantage is that only the surfaces of small components may beexamined, since larger ones would require a large quantity ofelectrolyte. Selective examination of specific regions of a surface ispossible only if the rest of the surface is covered by a lacquer. In thesecond type of cell, such as that disclosed by German Patent 197 49 111A1, the examination surface is pressed against a hole in the outer wallof an electrolytic container. To prevent the electrolyte from escaping,a sealing ring is utilized which delimits the area wetted by theelectrolyte. This method allows specific areas of the surface to bechosen selectively; however, the surface must be flat, and the size ofthe examined component is usually also restricted. A significant problemwith this type of cell is the gap created between the sealing ring andthe surface. In this gap, electrochemical inspection is possible only toa limited degree. In addition, this gap is the site in which crevicecorrosion tends to occur. The sealing ring therefore results inundesirably uneven performance. The use of silicon-coated glasscapillaries with a diameter in the range of 1 mm and smaller allows evenrough or uneven surfaces to be examined, since at this scale even curvedsurfaces appear flat. The silicon coating here also acts as a sealingring. However, since a microscope is used here to apply the capillary,here as well the size of the examined component is limited. Thefabrication and handling of capillaries is also expensive and ill-suitedfor industrial use. In addition, the problem of the sealing ring remainsunsolved.

[0005] For purposes of electrolytically inspecting a surface, acounter-electrode is required. An additional reference electrode isoften employed as well. These reference Electrodes consist of acontainer containing a saturated solution. In most commercial systems,these are potassium chloride solutions. This container of the referenceelectrode is usually enclosed by a porous glass body. The result is thatthe saturated potassium chloride solution is able to remain in contactwith the electrolyte, and any diffusion between the two bodies islimited. Over time, however, the potassium chloride will escape from thereference electrode and contaminate the electrolyte. This occurrence isespecially undesirable during corrosion investigations since chloridesare extremely aggressive. As a result, in currently used cells, theelectrolyte must be refilled before each measurement. The referenceelectrodes must also undergo regular maintenance. This procedurenecessitates in part the handling of aggressive substances. Thispreparation of the cell requires considerable care since even very smallair bubbles may prevent contact between the reference electrode andelectrolyte. Faulty measurements, or even destruction of the examinedsurface, may result from this.

[0006] East German Patent 263 829 A1 makes known an electrochemicalmeasuring cell. The cell body consists of an electrically conductive,chemically resistant material, contains the reference electrode andcounterelectrode, and accepts a small volume of aqueous electrolytesolution. The test sample is connected as the working electrode and islocated completely outside the electrode. The material and the chargecarrier exchange occurs through a semi-permeable sensitive wall. Thereference electrode and test electrolyte here must be reintroduced intothe cell before each use. The closed cell also entails problems withatmospheric pressure since the electrolyte is forced back through theporous wall in response to fluctuations in pressure, or is drawn out ofthe cell. If the cell is open, however, gravity causes the electrolyteto escape, unless extremely fine pores are used to prevent this.However, the fine pores cause an ohmic voltage drop which affects themeasurement.

[0007] It is not possible, or is possible only with great difficulty, toapply cells used previously to vertically oriented surfaces. The reasonrelates to gravity which causes air bubbles to move upward, therebypreventing electrolytic contact to the monitored surface.

DESCRIPTION OF THE INVENTION

[0008] The goal of the invention is to bring a defined electrolyte intocontact with a surface without the use of a sealing ring, therebycreating an electrolytic connection to a counterelectrode, and thuselectrochemically inspecting the surface locally by the application ofan electric current.

[0009] This goal is achieved according to the invention by thecharacteristic features of the first claim.

[0010] The essential feature of the invention is that a body utilizingcapillary action is applied to a surface. The body utilizing capillaryaction is hereafter called the tip. This allows an electrolytic contactto be created between the surface and a container. The capillary actionof the tip may be achieved in a variety of ways. For example, the entirebody may consist of a porous material such as nylon felt. Anothervariant involves the use of a body with one or more capillaries. Thecross-section of the tip is tapered toward the end. This feature allowsfor the minimum possible ohmic voltage drop. When the tip is applied,the electrolyte flows from the container through the tip and wets thesurface. The container consists of a porous material. The porosity isdesigned so that the capillary action prevents the electrolyte fromescaping, while at the same time enabling the maximum volume ofelectrolyte to be taken up. As a result, the greatest possible usefullife is achieved for the electrochemical cell. Any escape of theelectrolyte from the container and from the tip is prevented by theircapillary forces. The container is open during use so as not to preventthe electrolyte from flowing due to the build-up of any partial vacuum.Ideally, the container is closed off from the environment by a casing toprevent evaporation of the electrolyte. The casing is designed to remainopen during use to prevent any differences in pressure. Theelectrochemical cell may be easily closed by placing a cap onto it.Placing the tip onto a surface creates an electrolytic connectionbetween the surface and a counterelectrode which is immersed in thecontainer. The electrochemical potential of the surface may be modifiedby the flow of electrical current between the surface andcounterelectrode. In the case of chloride-containing electrolytes, asilver surface, ideally coated with silver chloride, is used as thereference electrode. A tungsten surface may also be used. By using amaintenance-free reference electrode which employs the measurementelectrolyte as the reference electrolyte, and by providing for completeclosure through the placement of a single cap, a maintenance-freeelectrochemical cell is created which is extremely easy to manipulateand may be prefabricated in ready-to-use form.

[0011] The advantage of the invention is that the any escape of materialfrom the electrochemical cell is prevented, with the use of a sealingring, by the capillary action of the tip and of the container, and thatthe surface is wetted with a defined electrolyte simply by removing thecap and applying the tip. Since both the subsequent flow of theelectrolyte to the surface and from the container to the tip is achievedexclusively by capillary action, the function of the electrochemicalcell is completely independent of the effect of gravity. The result isthat measurements can also be made on surfaces vertically orientedsurfaces. In addition, it is easily possible to perform measurements inzero gravity. Since the container is open, atmospheric pressure also hasno significant effect on the performance of measurements.

[0012] Since the cross-section of the tip is tapered toward the end andthe container has maximum porosity, a large volume is available toconduct the electrolytic current in the container and in the tip. Theohmic voltage drop thus occurs only at the very end of the tip. As aresult, any distortion of the measurement by the ohmic voltage drop canbe minimized.

[0013] The cell can be easily applied to the examination surface sincewhenever the tip is lifted the electrolyte is prevented from escaping bythe capillary action of the tip. As long as the tip is not significantlydeformed when applied to the surface, the interface with the surface isonly at a single point. The gap area is thus smaller than when a sealingring is used where the entire periphery of the wetted surfaceconstitutes a gap. If, however, the tip is deformed by the pressure ofapplication, it conforms to the surface geometry and the entire wettedsurface then constitutes a gap. The uneven performance observed duringthe use of a sealing ring therefore does not occur at all, or only to asmall extent.

[0014] The use of a silver surface coated with silver chloride, or asilver surface, or a tungsten surface creates a very simple referenceelectrode which remains stable and completely maintenance-free formonths at a time. There is no possibility of contamination of theelectrolyte, such as occurs with most reference electrodes, by thesaturated potassium chloride solution. The result is that the completecell along with the electrolyte may be prefabricated. Operation isextremely simple and does not require a technician. No manipulation ofthe electrolyte is required. The entire procedure consists in theremoval of the cap from the electrochemical cell and application to theexamination surface. After use, the cap is replaced and theelectrochemical cell is ready for the next use.

[0015] Since any escape of material from the electrochemical cell isprevented by the capillary action of the tip even without the tip'scontacting the surface, the electrochemical cell is extremely simple tomanipulate. It may, for example, be held in the user's hand and appliedto the highly curved surface of any large component (computer chip,automobile, pipeline, etc.). Since the interface of the tip is only at asingle point, or the tip conforms elastically to the surface, any typeof curved surface geometries may be examined. When a sealing ring isused, the surface must allow for a circular interface of the sealingring, a fact which results in certain requirements in terms of flatnessor surface radius. The surface of the component is wetted locally withelectrolyte, thus allowing electrochemical investigations of localresolution. This type of simple operation was previously impossibleusing conventional electrochemical cells for large components withcomplex geometries and vertically oriented surfaces. With the invention,for example, the quality of a welding seam on a pipeline may be easilyinspected without having to cut out the welding seam, grinding it flat,and inserting it into a classic cell. Thanks to the invention, it istherefore possible to conduct electrochemical investigations in astandardized routine fashion as a nondestructive test method in qualityassurance, research, etc. Since no measures related to sealing, such assealing rings, are required, the tip may be moved continuously along thesurface, thereby allowing for simple electrochemical inspection of largesurfaces with local resolution. Multiple sequential spot measurementsare also easily performed. The electrochemical cell may be employed fora multiplicity of electrochemical investigations and processes. Aftercompletion of the electrochemical modification, the electrochemical cellis simply lifted from the surface and closed. When lifted, any escape ofmaterial from the cell is prevented by the capillary action of the tip.The electrochemical cell may be stored for long periods in a closedcondition and used at any time without any preparatory efforts. Thismeans a great savings in time when conducting electrochemicalmeasurements. In addition, the electrochemical cell may be commerciallyprefabricated complete and ready to use, thus enabling its use in astandardized routine manner.

[0016] During prolonged measurements, the electrolyte is able toevaporate at the tip, thus leading to an increase in concentration. Thismay be prevented by surrounding the tip by a jacket. A high level ofhumidity is quickly established within the jacket which prevents anyfurther evaporation. As a result, prolonged measurements may beperformed with the electrochemical cell. The jacket may also be providedwith additional functions. It may, for example, be composed of aconductive material, thereby creating an electromagnetic shield for thecell or the conductive contact with the surface. By additionallyutilizing a spring, the jacket may also be used to ensure a constantapplication pressure. This feature enhances the reproducibility ofmeasurements and the useful life of the tip.

[0017] Due to its porous structure, the tip prevents any convection ofthe electrolyte. For processes which are controlled by mass transfer,such convection produces poor reproducibility and prevents meaningfulfindings. In the tip, the subsequent transfer of the initialconstituents for the electrochemical reactions is controlled almostexclusively by diffusion. This means that reproducible results areobtained. Use of the invention enables characterization of the masstransfer processes to be significantly improved.

[0018] **During certain types of electrochemical investigations, variousreaction products are formed on the surface. Since the tip permitspractically no convection, these reaction products are not dischargedbut are instead concentrated. This problem may be very simply remediedby stretching a porous sheet-like material such as a fabric over thetip. Hereafter this porous sheet-like material is identified as a poroussheet. The electrolyte emerges through the tip and the surface wetted asbefore. The electrochemical inspection of the surface is thus in no wayrestricted. However, the electrolyte is carried away laterally due tothe capillary action of the porous sheet. Due to evaporation on thelarge surface of the sheet, a continuous electrolyte flow is createdwhich carries the reaction products away laterally. As a result, asimple-to-manipulate flow-through cell is created. The addition of anelectrode which contacts the sheet allows the composition of theelectrolyte to be electrochemically characterized. An additionalpotentiostat, or ideally, a bipotentiostat, is required for thispurpose. Ideally, the tip is mounted in the casing by force fit. The tipis inserted into a tube which is provided with a thread, the walls ofwhich are elastically deformed in a radial direction. This elasticdeformability is ideally created by longitudinally oriented slots. Theopening in the casing is conical so that the diameter shrinks as thetube is screwed in. Screwing the tube with the tip into the casing thuscauses a force fit. As a result, the tip may be easily replaced at anytime.

[0019] Additional advantageous embodiments of the invention are found inthe subclaims.

BRIEF DESCRIPTION OF DRAWINGS

[0020]FIGS. 1, 3, 4 and 5 show sample applications of theelectrochemical cell. Identical and analogous elements are identified bythe same reference symbols.

[0021]FIG. 2 illustrates electrochemical measurements at differentpoints on a component made of stainless steel (DIN 1.4529) including awelding seam. The horizontal axis shows the electrochemical potential,recalculated for a saturated calomel electrode (SCE), while the verticalaxis records the current density.

[0022]FIG. 6 illustrates an electrochemical measurement of aheterogeneous surface made by automatic scanning using theelectrochemical cell. The measurement surface is 18×18 mm. The valueshown is the current density at a constant electrochemical potential of0.16 V SCE. Maximum current density is 5 μA.

METHODS OF IMPLEMENTING THE INVENTION

[0023]FIGS. 1, 3 and 4 show the electrochemical cell 1 consisting ofelements 2 through 6. A tip 6 is in contact with an open containerconsisting of a porous material 3 containing the electrolyte. Container3 is surrounded by an open casing 4 including an opening 18 in order toreduce evaporation of the electrolyte. The tip consists of a bodyutilizing capillary action, the cross-section of which is tapered towardthe end, thereby reducing the ohmic voltage drop to a minimum level. Thecapillary action may be achieved, for example, by a body consisting of aporous material or by a body having one or multiple capillaries of agiven cross-sectional area. The tip may, for example, consist of pressednylon felt, a fiber bundle, or two concentric plastic cylinders with acylindrical gap. It is also possible to fabricate the container and tipout of the same body. For example, a nylon felt used as a container maybe compressed on one side by hot-press molding to form a tapered tip.The capillary action is such that the electrolyte is prevented fromescaping when the tip is lifted. When the tip is applied to surface 7,the electrolyte flows from the container through the tip and wets thesurface locally. Any escape of the electrolyte 15 from the container isprevented by the capillary action between surface 7 and tip 2, as theenlargement of the tip in FIG. 1 shows. The enlargement shows the caseof a tip which is not deformed upon application. As a result, only asmall gap is created. Preferably, the tip has a smaller diameter at theend than at the connection point to container 3. The container consistsof a porous material or another material with capillary action such asfelt. A counterelectrode 5 is installed in this container and is incontact with the electrolyte. This counterelectrode consists of anelectrically conductive, preferably inert, material such as platinum,graphite, gold, silver, titanium or stainless steel. Thecounterelectrode is connected in an electrically conductive manner witha current source 8 such as a battery, a potentiostat, or a galvanostat.This current source is also is also connected in an electricallyconductive manner to the examination surface. The flow of currentbetween surface 7 and counterelectrode 5 causes the surface in thewetted region to be electrochemically modified. The tip may be movedover the surface continuously or in steps, thereby electrochemicallymodifying different regions of the surface.

[0024] Both the wetting of the surface and the flow of electrolyte 15 iseffected by the capillary action of the tip and container. As a result,the operation of the electrochemical cell is independent of the effectof gravity. Use on vertically oriented surface and in zero gravity iseasily possible.

[0025] Installation of a reference electrode 6 additionally allows formeasurement of the electrochemical potential of surface 7. Withchloride-containing electrolytes, this reference electrode may consistof a silver surface which is ideally coated with silver chloride.

[0026] Using the described electrochemical cell 1, it is possible toautomatically scan larger surface areas in order to determine theirelectrochemical properties. In this manner, local weak points andinhomogeneities on materials may be detected quickly and simply. As aresult, the electrochemical cell is suited for routine investigations insurface engineering.

[0027] In order to prevent any uncontrolled evaporation of theelectrolyte, any exchange of air with the environment is prevented by ajacket 9, as shown in FIG. 3,. This jacket 9 may, for example, consistof a solid plastic cylinder or a soft rubber sleeve. The essentialrequirement is that it contact the surface and prevent any exchange ofair with the environment, or at least strongly inhibit this. Theadditional use of a spring 10 allows a constant application pressure oftip 2 on surface 7 to be obtained. If the jacket consists of anelectrically conductive material, it may be also employed as shieldingagainst electromagnetic fields and/or for the purpose of electricallycontacting surface 7.

[0028] As shown in FIG. 4, the use of a porous sheet 11 such as a nylonfabric allows for the flow of electrolyte, and thus for a continuousrenewal of the electrolyte on the examined surface.

[0029] The design described makes possible a multiplicity ofelectrochemical investigations and methods, while the lateral resolutionroughly matches that of the surface wetted by the electrolyte. Thefollowing discussion illustrates a few of these investigations andmethods.

[0030] The use of current density potential measurements allows forelectrochemical characterization of the surface and for determination ofthe resistance of a material against local corrosion.

[0031] By recording impedance measurements, the rate of corrosion may bedetermined with minimal effect on the surface. In addition,semiconductor properties such as flat band potential and dopingconcentration may be determined for semiconductors. In the case ofcoatings, charge transfer resistance and capacitance may be analyzed.

[0032] Coatings may be applied locally by electrolytic deposition. Forexample, copper, polypyrrole or other substances may be applied locallywithout any masking of the surface using photolithography. Conversely, alocal etching process may be implemented by electrolytic dissolution.

[0033] Since the tip is moved continuously or in stepwise fashion overthe surface, material parameters (such as capacitance or charge transferresistance) may be determined with lateral resolution. In addition,structures such as conductive tracks may be drawn on surfaces byelectrolytic deposition. The electrochemical cell may be commerciallyprefabricated, both inexpensively and complete, or at least in part.Since the cell may be used immediately without any preparation, there isa significant savings in time. After measurement has been completed, theelectrochemical cell may be closed until the next measurement isperformed. Thanks to the stability of the reference electrode, long-termstorage is possible, and no kind of preparation is required forsubsequent measurements.

[0034]FIG. 1 illustrates an sample application of the invention. Tip 2is connected to container 3 which contains 1 M NaCl solution. Thesolution is prevented from evaporating by casing 4. A platinum wire isimmersed in the electrolyte forming counterelectrode 5, as is a silverwire coated with silver chloride forming reference electrode 6. Theseelectrodes are connected through terminals with a potentiostat 8 whichis also connected to surface 7 of a welded component, consisting in thisexample of stainless steel (DIN 1.4529). When the tip is applied to thesurface, the 1M NaCl flows from the open container through the tip andwets the surface in the area in contact with the tip. This creates anelectrolytic connection which enables electrochemical inspection of thesurface by passing a current between counterelectrode and surface. Thetip is applied at different locations on the component. Using thepotentiostat to measure current density potential curves, the resistanceof the materials is analyzed at these locations. The results are shownin FIG. 2. Over the entire potential range, there is no occurrence ofpitting either in the base material (a) or in the welding seam (c). Incontrast, a significant current rise indicating the poor resistance ofthis region against local corrosive attack is found in the heat affectedzone (b) at even low potential values. This shows clearly that thewelding parameters must be improved to achieve a higher corrosionresistance in all regions. After measurement is complete, theelectrochemical cell may be re-closed until the next measurement.Storage over long periods of time is possible, and no kind ofpreparation is required for later measurements.

[0035] During prolonged investigations, it is critical that anyevaporation of the electrolyte through jacket 9 be prevented. This ispossible by using a jacket 9 such as that shown in FIG. 3. Any exchangeof air with the environment is significantly reduced by jacket 9 so thatthe air around the tip becomes saturated very quickly by evaporation ofthe electrolyte. Any further evaporation is halted as a result. Ifjacket 9 is also composed of a conductive material, it may be employedsimultaneously as a shield and to contact surface 7. By employing aspring 10, jacket 9 may also be used to set a reproducible pressure ofapplication.

[0036] An sample application for measurements during electrolyte flow isshown in FIG. 4. By using a porous sheet 11, such as a nylon fabric, theelectrolyte is drawn away by the capillary action of the sheet from thecontact area on the surface. The continuous evaporation on therelatively large surface of the porous body allows a continuous flow ofelectrolyte to be obtained. As a result, the reaction products arereadily removed. If the sheet is in contact with an electricallyconductive, preferably inert, material, the composition of the removedelectrolyte may also be electrochemically analyzed. The function of theelectrode may then be taken over, for example, by jacket 9. In the caseof this configuration, a bipotentiostat 12 is employed.

[0037]FIG. 5 is a constructional diagram of the electrochemical cell.Tip 2 along with tube 13 is screwed into open casing 4. This achievesthe force fit of tip 2 which allows for simple replacement of tip 2.Mounting cap 14 closes off opening 18 and tip 2. The electrochemicalcell 1 is thus maintenance-free and ready to use over extended periodsof time.

[0038]FIG. 6 illustrates a measurement on a thermally sprayed coating.The electrochemical cell here was moved continuously over theexamination surface. The examined surface measured 18×18 mm. Thevertical axis shows the current density at a constant electrochemicalpotential of 0.16 V recalculated against a calomel electrode. Themaximum value for the current density is 5 μA for a measurement surfaceof 0.25 mm². It is evident in the sample application shown that thereare two types of defect present in the coating. One involves isolatedpinholes 16, the other two-dimensional defects 17 which may beattributable to cracks and poor adhesion of the coating. Based on themeasurement, it is clear that parameters of fabrication have to beoptimized. Of course, the invention is not restricted to the sampleapplications shown and described here. For example, the electrochemicalcell may be also used to conduct potentionstatic and galvanostaticretention tests and crack tests. In addition, impedance measurments maybe performed; and electrodeposition and electrodissolution are alsopossible. The potentiostat may, for example, be replaced by a simplervoltage source such as a battery.

[0039] The essential point is that by applying the tip the surface islocally wetted by a defined electrolyte flowing from an open porouscontainer, and that the surface is electrochemically modified by anelectrical current flowing between the surface and the counterelectrode.

1. Electrochemical cell (1) for electrolytically contacting a surfacewith a defined electrolyte (15) and for electrochemically modifying thesurface (7) by supplying current (8) between the surface (7) and acounterelectrode (5), with a body utilizing capillary action (2) beingapplied to the surface (7), with the electrolyte flowing from acontainer (3) through the body utilizing capillary action (2) onto thesurface (7), and with the electrolyte locally wetting the surface,characterized in that the container (3) consists of a porous material.2. Electrochemical cell (1) according to claim 1, characterized in, thatthe container (3) is surrounded by an open casing which reducesevaporation of the electrolyte, the open casing being closable. 3.Electrochemical cell (1) according to claims 1 or 2, characterized in,that the counterelectrode (5) is immersed in the container. 4.Electrochemical cell (1) according to one of claims 1 through 3,characterized in that the body utilizing capillary action (2) has across-sectional area tapered toward the front.
 5. Electrochemical cell(1) according to one of claims 1 through 4, characterized in that areference electrode (6) is immersed in the container (3). 6.Electrochemical cell (1) according to claim 5, characterized in that thereference electrode (6) consists of a silver surface coated with silverchloride or a tungsten surface.
 7. Electrochemical cell (1) according toone of claims 1 through 6, characterized in that evaporation of theelectrolyte from the body utilizing capillary action (2) is prevented bya jacket (9).
 8. Electrochemical cell (1) according to one of claims 1through 7, characterized in that a porous sheet (11) located between thebody utilizing capillary action (2) and the surface (7) causes a flow ofelectrolyte at the surface (7).
 9. Electrochemical cell (1) according toclaim 8, characterized in that the porous sheet (11) is in contact withan electrically conductive electrode (9).
 10. Use of the electrochemicalcell (1) according to one of claims 1 through 9 to modify theelectrochemical potential of the surface (7).
 11. Method forelectrolytically contacting a surface with a defined electrolyte (15)and for electrochemical modifying the surface (7) by supplying current(8) between the surface (7) and a counterelectrode (5) of anelectrochemical cell, with a body utilizing capillary action (2) beingapplied to the surface (7), characterized in that the electrolyte flowsfrom a container (3) made of a porous material through the bodyutilizing capillary action (2) onto the surface (7), and that theelectrolyte locally wets the surface (7).
 12. Method forelectrolytically contacting a surface with a defined electrolyte (15)and for electrochemically modifying the surface (7) according to claim11, characterized in that the electrochemical cell (1) is movedcontinuously over the surface (7) to be characterized.